With the shale gas boom holding out promise of a revival of the US economy, an Environmental Protection Agency report that said the drilling process of hydraulic fracturing may have contaminated ground water in Pavillion, Wyoming led to much concern in the country. However, the study is not definitive and it does not apply to the rest of the country.
"When considered together with other lines of evidence, the data indicates likely impact to ground water that can be explained by hydraulic fracking," said the EPA report.
It referred to the drilling process that blasted water and chemicals into shale rock to release oil and natural gas. The news was widely welcomed by environmentalists and many in the media who had been clamouring for an end to fracking.
Analysts say over a-third of all natural gas drilling now employs fracking, with the percentage set to rise. If the findings of the EPA Wyoming study are established in a scrutiny, an industry that employs tens of thousands could be in peril.
This is the first major study to have established a link between fracking and ground-water pollution, but the EPA draft has not been peer reviewed by independent scientific analysts. The study is already under attack by critics, which Wyoming governor Matt Mead called "scientifically questionable."
According to the EPA, it launched the study in response to complaints "regarding objectionable taste and odour problems in well water." What it left unsaid was that the US Geological Survey had detected organic chemicals in the well water in Pavillion (population 175) for at least 50 years - long before fracking was employed.